Okay, the theory, for those that don't already know, is that a planet called Niberu will pass into out solar system in 2012, and has done this periodically (I think 30,000 years is the rough interval) and that its passing can cause an E.L.E., or an Extinction Level Event, where almost all species on the planet die out.

Either it smashes through the oort cloud and peppers us with meteors, hits us with its tail of debri, or stimulates the sun in a way to assault Earth with solar storms.

I don't really claim to understand this much, but the video dumbed it down enough for me. I'm silly, I know ^___^ Urd explained to me over the course of a few hours how this totally cannot happen, and that the video ignores some key factor (like, uh, the rest of the planets) but I thought it was post worthy.

Nibiru is essentially plausible, it's just hard to take seriously because it's often touted by people that sleep in rock crystal beds built inside pyramid shaped frames that are likely to be calling up George Noory at 3AM to explain how they've been in communication with aliens from Vulcan, or have evidence that a great interplanetary civilization used to exist on Phaeton, the relics of which survived to form the basis of our own (both worlds also being hypothetical planets).